Domain Registration

All registered domains are saved in a database called domain name registry.  And it part of the DNS of internet that have the registered domain name in a database.  Domain name registration based on FCFS (First Come First Serve) and registries may have their local languages on their web sites.  Sub-Domain registration is nothing but they can use their domain for sub domain registration. For example javamain.com this is main domain and sub domain is app.javamain.com